/**
 * Given two integers n and k, return all possible combinations of k numbers out of 1 ... n.
 * For example,If n = 4 and k = 2, a solution is:
 * [
 * 	[2,4],[3,4],[2,3],[1,2],[1,3],[1,4],
 * ]
 */
/**
 * @author Ivan
 *
 */
package problem77_Combinations;